Question

Which of the following angles can be used to evaluate cot(-210°)

Answer 1

cot (- 210º) = - √3 so 30°

Answer 2

-
`√(3)`

Explanation:

We know that cot (-x) = -cot x

therefore cot(-210) = -cot(210)

and we know that cot (180+x) = cot(x)

[since 210 lies in third quadrant therefore its positive ]

therefore cot(180+30 ) = cot 30

so here in the question

cot(-210) = -cot(210) = - cot (30)

= -
`√(3)`